Recommended Posts

Having posted a little about my issues with the adaptive high beams on the PHEV thread, I'm interested to find out more from other UK PHV owners about whether your adaptive high beam lights work as described in the brochure:

Point 1: ❌ Mine do not operate like this at all. There is no narrowing or widening of the beam depending on the speed. They simply do not operate at all until I reach 40mph.

Point 2: ✔️ The shuttering seems to work very well - as described here.

Point 3: ✔️The height adjustment also seems to work fine, as described here.

Point 4: ❌ Mine do not operate like this at all. There is no steering whatsoever.

Please post your experiences below. I'd like to know whether my lights are just misconfigured / defective or whether Toyota have crippled the UK spec of the AHB function in the same way they appear to have crippled the charging Climate Prep function.

Share on other sites

I'm interested too. I've not driven in the dark enough to be able to add anything at the moment. The high beam does dip for oncoming vehicles, but as to this specific 4 items - I've not observed enough.

Share on other sites

I really like the shuttering effect, but now that I'm driving both ways in the dark each day, I can't cope with not having main beam at all below 40mph. I've therefore resorted to manual.

Next time you head out in the dark, see if pushing the stick forward to the main beam position when you're on Auto does anything at all below 40mph. It does absolutely nothing for me, then as soon as the speedo hits 40 exactly, they fire up!

Share on other sites

Inconclusive. Lights were on during a quick GP trip in overcast conditions. Beam worked at all speeds, but it can't have been the auto-beam.

Your observation on speed limit would tie in with what annoyed me with the RAV4 - when I needed beam on slow rural road it wasn't there. It never occurred to me there was a limit - I naively thought it had something to do with the closeness of the sides reflecting back to the sensor.....

Strange how it differs from model to model - my Prius Gen 4 ordinaire switched to high beams from 27 mph during the brief period I tried the feature, but for reasons previously mentioned it's permanently switched off.

27's bad enough on some local country lanes, but 40! Impossible!

On another tack, the (non-adaptive) Cruise Control on my Gen 1, 2 & 3 Prius could be set to any speed from 25 mph upwards, but the adaptive on the Gen 4 is 28 mph upwards.

Inconclusive. Lights were on during a quick GP trip in overcast conditions. Beam worked at all speeds, but it can't have been the auto-beam.

Your observation on speed limit would tie in with what annoyed me with the RAV4 - when I needed beam on slow rural road it wasn't there. It never occurred to me there was a limit - I naively thought it had something to do with the closeness of the sides reflecting back to the sensor.....

Would using a Carista give access to alter features you cannot normally get to?

Sadly not. The only option it shows for headlights is 'lights on in residential mode'. Changing that doesn't appear to do anything obvious - it's possibly responsible for shutting off main beam when it detects street lighting, but I'm not sure. As described above, that does sometimes seem to happen, but not consistently. Either way, this setting has no effect on the speed at which the main beams switch on, which remains precisely 40mph.

It's a bit odd that none of the AHB options listed in the manual as changeable by a dealer show up in Carista at all. It would appear that the steering around corners function could be enabled by a dealer (although it should be on by default anyway). However, there is no setting that would seem to have an impact on operating below 40mph. I'm not sure what the 75mph mode change might refer to - I'm guessing it's 'high speed mode' as described above in the manual, but I've actually never been that fast! Is it significant that a speed for 'low speed mode' is not listed at all? Does that mean it was cut from UK spec? Who knows.

I have found what appears to be a press release document for the UK which describes low-speed mode as operating between 9 and 25mph, although I'm not sure this document can be trusted as it also lists seven available colours for the PHV and witters on about some nonsense called 'Driver's Mind Logic' when in Power mode! Seriously, who makes up this stuff?!

... possibly responsible for shutting off main beam when it detects street lighting

...75mph mode ..., but I've actually never been that fast! ...

Accosing the the manual, AHB on the non-plugin Prius is supposed to take into account street lighting, oncoming traffic and rear lights of cars in front in making it's decisions (and nowhere refers to the speed below which it refuses to switch to highbeams).

During the few weeks I experimented before permanently switching it off, I did find it quite consistently reacted well to street lighting, but was very poor at being considerate to cars in front unless they were very close, and almost useless in dipping quickly (or at all) for oncoming traffic except on fairly straight single carriageways.

Accosing the the manual, AHB on the non-plugin Prius is supposed to take into account street lighting, oncoming traffic and rear lights of cars in front in making it's decisions (and nowhere refers to the speed below which it refuses to switch to highbeams).

During the few weeks I experimented before permanently switching it off, I did find it quite consistently reacted well to street lighting, but was very poor at being considerate to cars in front unless they were very close, and almost useless in dipping quickly (or at all) for oncoming traffic except on fairly straight single carriageways.

Of course, to do a true 75 mph, you'd see over 80 on the speedo.

Interesting comments. I've yet to dark drive in my PHV, but both my RAV4s were reliable on beam dip, I'd say about 95% of times - and yes, corners were their weak spot, which is not surprising. But Jay has provided a reason why I couldn't understand the auto-beam not working on slower (<40) rural roads where, arguably, they're almost a necessity!

...Jay has provided a reason why I couldn't understand the auto-beam not working on slower (<40) rural roads where, arguably, they're almost a necessity!

Absolutely - on my non-plugin they work from 27 mph (strange they chose different speeds), and even that is plain dangerous on some of the pitch black, very twisty, high banked and tree-lined single track roads near me. I needed to be able to see enough to get to 27, and until I stopped trying out the AHB found myself trying to hold the headlight flasher stalk while working overtime with the steering wheel!

Share on other sites

In the dark(ish) garage the lights twitch until they settle down, presumably auto adjusting for level.

On the open road - still not totally dark, and I only had around a mile of rural twists in which to work with. Auto beam activated at 41mph and deactivated at 23. I didn't see any of the other adaptives working.

Share this post

Link to post

Share on other sites

Up until now, I’ve thought the adaptive headlights on my Gen 4 Prius plug-in worked well but, this morning, I had countless cars coming towards me flashing their lights because mine weren’t dipping quickly enough - and they were right: I could tell the lights were slow to react. This was around 7am so still properly dark. No idea why I should suddenly have this problem because it’s not been an issue before and, as far as I can tell, their sensitivity isn’t adjustable unless someone knows different? Anyone else had this problem?

Up until now, I’ve thought the adaptive headlights on my Gen 4 Prius plug-in worked well but, this morning, I had countless cars coming towards me flashing their lights because mine weren’t dipping quickly enough - and they were right: I could tell the lights were slow to react. This was around 7am so still properly dark. No idea why I should suddenly have this problem because it’s not been an issue before and, as far as I can tell, their sensitivity isn’t adjustable unless someone knows different? Anyone else had this problem?

If the windscreen was misted up slightly it might have been affecting the camera. This usually prompts an error message on the MFD, but if it was only slightly misted it might throw its judgement off without triggering the error.

Mine will occasionally have a tizz and not shutter properly, dazzling other drivers. This is rare, though. There are also certain stretches of road where the AHB will shut off main beam completely for no reason - same location each time, no other cars around. There's one particular junction where the main beam will shut off, then flash on again briefly, then shut off for a few seconds before coming back on, every time I hit that stretch of road.

I'm just dipping manually with the stalk now because so much of my driving is at slow speeds and the main beams simply won't come on if AHB is switched on. I presume yours are the same in not operating below 40mph?

Share on other sites

One night I'll really test these things! But it's odd, from what I've seen so far, the auto-beam doesn't react as well as the RAV4 did - unless it's something simple such as height above the road, the PHV is a real drop down 😄

The PHEV AHB seems to differ in operation to my Prius ordinaire too, but that's not surprising seeing as the PHEV's headlights are considerably higher spec than mine.

There are almost no circumstances where mine dips acceptably quickly or reliably for my conscience and although mine will come on from 27 mph and stay on slightly below this, that's not enough on some of the local country lanes. Mine have been permanently switch to manual since the first 2-3 weeks I had the car.

Share this post

Link to post

Share on other sites

Excellent point about potentially the windscreen being misted up and therefore the AHB not working properly because I’d probably only driven a mile or two at that point. What would have made it worse was pre-heating the car before I set off which always seems to cause all windows to be fogged up when I first get in it and takes some clearing. Coupled with the fact they most certainly don’t work at low speeds, which I really need around our country lane, I think I’ll give up and switch to manual. &#33;Removed&#33; frustrating.

Share on other sites

By means of an update, I have now had confirmation from Toyota UK that the Auto High Beams do not operate in the way one would expect from the brochure. My car is therefore definitely not faulty.

The main beams engage at 37mph and disengage at 25mph. Below those speeds, only dipped beams will work. That is exactly what my car does, accounting for speedo error. The 'low speed mode' in the brochure doesn't exist - it's just referring to dipped beams!

The cornering function ONLY applies to the high beams, not dipped. I have to say, I'm still not convinced mine does any corner illumination at all, but then the corners I would actually find this useful on are all taken below 37mph, so I may just not have noticed.

I can't imagine who thought either of the above setups was acceptable, but that is definitely how they are 'supposed' to work. I have also discovered that there is a new manual (not brochure) which more accurately describes the AHB operation. However, to download this manual from the Toyota website, you have to tell the website that your car was manufactured after January 2018, even if it wasn't!

I am still none the wiser about the 'high speed' function, as I have yet to find an unlit road with no oncoming traffic where I would safely be able to reach 75mph. However, it was the low-speed operation which I took issue with, and thanks to PhilT's post about adjusting the headlight units upwards this is actually no longer a concern. I hadn't realised just how bad the dipped beams were until I adjusted them, and they can now be used safely on unlit roads up to ~45-50mph without needing main beam at all and without annoying other drivers.

Share on other sites

Confusingly we couldn't work out what was happening yesterday evening. I guess the shuttering was activating as not that many cars were showing annoyance. Often the nearside lights would remain high, the lights of on-coming cars made it difficult to see if there was any shuttering/adjustments - there were a lot of false alarms due to reflective road signs and one or two occasions when the lights would just flash because they wanted to!

The blue high beam light remained on at all times, except when speed dropped below 25 and stayed off until 41. This was disconcerting as with it on one assumes the beams haven't dipped.

Confusingly we couldn't work out what was happening yesterday evening. I guess the shuttering was activating as not that many cars were showing annoyance. Often the nearside lights would remain high, the lights of on-coming cars made it difficult to see if there was any shuttering/adjustments - there were a lot of false alarms due to reflective road signs and one or two occasions when the lights would just flash because they wanted to!

The blue high beam light remained on at all times, except when speed dropped below 25 and stayed off until 41. This was disconcerting as with it on one assumes the beams haven't dipped.

The blue light is a bit pointless in the way that it operates. I suppose it's done that way because the lights don't actually 'dip' at all, but it would be more reassuring if it changed when the shuttering activated.

After adjusting the beams up, I don't use AHB at all any more. In fact, I rarely bother with manual main beam other than for the occasional joy of lighting up something that's half a mile away.